Feeding negatively impacts fishes in several ways. Often, the foods provided are not types that fishes naturally encounter or are equipped to process (Perrine 1989). As a recent report (Maldives 2004) states:
"In the majority of cases, the food that is fed to these fish is radically different from their normal diet. As a result of fish feeding, some very large humphead wrasses died after being fed dozens of eggs, while a great many soldierfish choked to death after wolfing down chicken bones. Large basses have been seen to tear little sacks of food right out of the scuba diver's hand, devouring both sack and contents."
Even frozen fish may prove harmful or lethal; the deaths of fed wild dolphins have been linked to bacteria of a type frequently associated with spoiled fish (NMFS 1994).
Feeding has been shown to disrupt or alter normal
distribution/abundance patterns and behavior of marine fishes. The US state of Hawaii (Hawaii DLNR 1998)concluded, "Fish feeding has been shown to change the species composition in areas where the practice is done regularly, and fish become much more aggressive." Some species form disorganized swarms that surround and aggressively approach, follow, and often nip at divers (Perrine 1989; Hultquist 1997). Normally reclusive species (e.g., sharks, moray eels, groupers) may approach and follow divers even near the sea surface, making them easy targets for underwater hunters and poachers (Quinn and Kojis 1990; Cole 1994).
Fish feeding has the capacity to alter fundamental ecosystem attributes at feeding sites, with unknown long-term impacts on affected marine communities. Benthic habitat damage (including loss of gorgonian corals) has been attributed to divers feeding fishes within Mediterranean MPAs (Zabala 1996). Australian MPA managers (GBRMPA 1999) expressed concern over fish feeding in coral reef areas: "The unnatural addition of organic matter and nutrients to reef waters may have adverse environmental impacts, e.g., damage to coral caused by excessive growth of algae." Hawaiian MPA managers reported a case in which fish feeding changed the fish community and degraded water quality: "The feedings caused a naturally balanced ecosystem to turn into something of a petting zoo...so much that it is no longer considered a 'normal' reef ecosystem." (Hawaii DLNR 1999)
The feeding of wildlife has long been recognized by terrestrial wildlife managers as a serious problem, and is expressly prohibited in all US and Canadian national parks and wildlife refuges, as well as many localized jurisdictions. The number of divers and snorkelers worldwide interacting with marine wildlife within MPAs now numbers in the millions annually, and the cumulative impacts of such multitudes cannot be ignored. Because the US Marine Mammal Protection Act of 1972 (as amended) formally defines "feeding or attempting to feed" a wild marine mammal as "harassment", such activities are illegal in US waters. Where MPA management goals include the preservation and/or protection of natural habitats and wildlife, these same common-sense protections should logically be extended to fishes and other marine wildlife as well.
